1. Industrial Application Field
The present invention relates to a microwave oven which has a built-in microcomputer and which is operated according to cooking programs stored in a memory device.
2. Description of Background
As the heating functions of microwave ovens have been developed, the number of usable heating and cooking methods has increased, and the range of cookable menus has expanded. As the number of cooking menus has expanded, many menus have been automated through microcomputer control of microwave heat cooking, conventional heat cooking, and combination microwave and conventional heat cooking. For the purpose of the operator's being able to easily use these automatic heat cooking methods, menu keys and other selection functions have been provided on the control unit as will be described below to call the cooking program associated with a specific menu selection.
FIG. 8 shows the external appearance of a conventional microwave oven. Numeral 31 is the outer cabinet, 32 is the control unit, 33 the oven cavity, 34 the oven door, 35 the oven tray, and 36 the heating element.
FIG. 9 is an enlarged view of the panel on control unit 32. This panel is comprised of the following elements. Specifically, display 38, heating key 39, first menu keys 40, cancel key 41, second menu keys 42, door 43, heat mode selector keys 45, and timer control 46. As shown in FIG. 10, the operating unit containing the first and second menu keys and other controls of control unit 32 is comprised of an overlay 47 imprinted with the outlines of the menu keys and/or the names of the menu keys with an electrical contact provided to the back side of each key, a circuit board 50 provided with input switches, a membrane sheet 48 which assures a positive connection between the contact on overlay 47 and the corresponding input switch on circuit board 50 when overlay 47 is pressed at a specific key position, and a spacer 49.
However, in a conventional microwave oven in which heat cooking has been automated, multiple menu keys 40, 42 are provided on the control unit 32 so that the user can easily select the desired cooking program. The proliferation of so many keys and buttons however, conversely makes the menu heys 40, 42 small and makes the menu display confusing and hard to read, and it is therefore not easy to quickly find and select the desired menu key. As a result, a door 43 is used to hide the least frequently used second menu keys 42 from the sight of the user, but while this is intended to make operation easier, it conversely makes operation more complicated. Furthermore, since menu keys 40, 42 become small, the operator not infrequently may also press the menu key beside the desired menu key 40, 42.